1. Field of Invention
The present invention relates to oil-filled, pad-mounted electrical distribution transformers and in particular to a tank for such transformers.
2. Brief Description of the Related Art
Transformers are immersed in one or more liquid or gaseous fluids or combinations of both to ensure their electrical isolation or refrigeration. In order to keep the transformer immersed in one or more fluids, it is required to be contained in a tank.
A conventional tank for a transformer is a generally cube-shaped or rectangular structure that consists substantially of four lateral walls, one horizontal base, and one horizontal cover. The depth, width, and length of the tank is governed by the necessary electrical and mechanical clearances for the core and coil of the transformer. As such, the internal volume of the tank typically ends up so large that it is necessary in some cases to add reinforcing members to prevent the lateral walls and base from being deformed by internal and external pressures. In addition to problems with maintaining the integrity of the tank, because of their size, conventional tanks are expensive to manufacture and to transport.
Variations to the conventional transformer tank structure in the prior art addresses some of these limitations. For example, U.S. Pat. No. 5,527,988 to Hernandez et al. teaches a pad-mounted transformer tank, comprising six vertical walls, designed to increase the strength of the tank and decrease the required oil volume. U.S. Pat. No. 7,365,625 to Carrasco-Aguirre teaches a transformer tank with eight alternating curved vertical pieces and straight vertical pieces. This tank structure likewise decreases the required oil volume of the tank and is claimed to be easier to manufacture.
Even with the improved transformer tank structures of the prior art, considerable volume in the tank is wasted. The volume of the tank is directly related to the volume and cost of oil to occupy the tank, the amount and cost of steel to construct the tank, the weight of the tank, and the integrity of the tank. It would therefore be desirable to develop a pad-mounted transformer tank that is smaller, thus requiring less oil volume and less steel to manufacture. These limitations of the prior art are overcome by the present invention as described below.